1. Field of the Invention
The present invention relates to a micro-fluids switch with moving planes, especially relates to a mixed apparatus of passively mechanical design and hydrophobic property between fluids and micro-channels. Moreover, the goal of changing fluid channels can be achieved by means of simply relative motion between substrates.
2. Description of the Prior Art
Many contemporary products and processes have to be designed to let fluids flow in micro-channels. For example, in the field of molecular biology, biochemical experiments are always taken with biochips with micro-fabricated flow channels. Further, in the field of electronic products, an ink-jet head of a thermal ink-jet printer has many micro-fabricated flow channels to let ejecting ink be normally distributed. Obviously, it is an important issue about how to moderately control the fluid flowing in these micro-channels (especially about the switch of different fluids). Herein the so-called micro-channel is a fluid channel with a very small dimension (very small cross-section). For example, a diameter of a cross-section of a micro-channel usually is between 0.1 microns and 1000 microns.
Take bio-chip for example (as shown in FIG. 1A), the basic structure consists of a hollow hole 11 made on a substrate 10 for biochemical reaction, independently-input micro-fabricated flow channels 12 made on the substrate 10 and connected with the hollow hole 11, and an independently-output micro-fabricated flow channel 13 connected with the hollow hole 11 but disconnected with these independently-input micro-fabricated flow channels 12. In the practical application, different independently-input micro-fabricated flow channels 12 are used to separately transmit different fluids (such as different bio-developed fluids) to the hollow hole 11 and the independently-output micro-fabricated flow channel 13 is used to transmit the unnecessary fluids out from the hollow hole 11. Besides, because there are special needs in the bio-chemical experiments, these conditions of the fluid switch controlling in different state with different fluids passing through independently-input micro-fabricated flow channels must be satisfied as follows: (1) Different fluids in different independently-input micro-fabricated flow channels 12 cannot be mixed before arriving at the hollow hole 11. (2) The environmental changes (such as pressure change) of the hollow hole 11 caused by switching micro-fabricated flow channels should be diminished as less as possible. (3) The switch apparatus has to be easily-operated, stable, and repeatedly-used during long periods. (4) The switch process should not produce materials (such as materials, which will depress biochemical reaction) which will affect the environment in the hollow hole 11. (5) The switching apparatus must be separable. Besides, if we neglect the hollow hole 11 and only consider the one-to-many relationship between the independently-output micro-fabricated flow channel 13 and the independently-input micro-fabricated flow channels, the structure (and corresponding microfluidics switch) as is shown in FIG. 1A can also be applied to a ink-jet head used in a thermal ink-jet printer and so on.
In the prior technology, microfluidics switch can be divided into active and passive categories. As is shown in FIG. 1B, an active microfluidics switch is designed to let each independently-input micro-fabricated flow channels 12 connect different fluid sources 16 through different input tubes 14 and different switches 15, and let the independently-output micro-fabricated flow channel 13 connect outside through output tube 17. Therefore, fluids (output fluids though controlled output tube 17) entering the hollow hole 11 and participating biochemical reactions can be controlled by virtue of adjusting each on-off state of switches 15. Generally speaking, however, an active microfluidics switch always has some faults as follows: (1) produce it expensively. (2) Switching will have a great impact on the state of the hollow hole (instant change is more obvious). (3) Components passed by fluids will be contaminated and should be disposable. (4) The instant response of switching cannot show because of the long distance between the switch and the hollow hole.
As is shown is FIG. 1C, a passive microfluidics switch consists of an upside substrate and a downside substrate and the two substrates 10 are closely connected, and a hollow hole 18 is formed in the interface between the two planes 10. Besides, the hollow hole 18 used to input/output fluids with outside, micro-fabricated flow channels 19, and inter-medium 195 are formed separately between the two substrates. The flows of fluids in the micro-fabricated flow channels can be controlled by means of using inter-medium 195 to change flow direction of fluids, and the input/output fluids in the hollow hole 18 can be further controlled. Generally speaking, however, a passive microfluidics switch always has some faults as follows: (1) The matching design between the inter-medium and the micro-fabricated flow channels is so complicated that the inter-medium and the micro-fabricated flow channels cannot be fonned precisely. (2) The inter-medium always reacts with the fluids and then the reaction produces impurities (they will contaminate the hollow hole used as a reaction chamber and final output fluids), (3) The inter-medium always cannot react instantly with the effect of the flow direction change of fluids. (4) The process of connecting upside substrate and downside substrate always damages the micro-fabricated flow channels and the inter-medium.
Therefore, the known technology of switch apparatuses of fluids clearly has several problems needed to be improved. Hence, how to form good microfluidics switch when applying the technology or the product of “Let fluids flow in the micro-channels” is still an urgent problem to be solved.